MICROBIAL THERAPY is being used to control the tumor growth. However the control of the activity of the microbe faces several problems which limited its applicability. Therefore, the aim of the present study was to assess the possibility of controlling the activity of Pseudomonas aeruginosa by 650 nm diode laser beam; power density 150 mW/cm2, the spot area of the laser beam was 1 cm2, incident doses of 30 joules/cm2 was applied for 30 min per day. The tested mice were divided into 7 groups A, B, C, D, E, F and G. Group A was used as control, group B injected in the right thigh by 0.2 ml from a suspension containing 106 cell /ml of the Ehrlich tumor, group C injected with 4x109 CFU of Pseudomonas aeruginosa. group D injected in the right thigh by 0.2 ml from a suspension containing 106 cells/ml of the Ehrlich tumor and exposed to Laser radiation for 30 min /day along four successive days. The group E injected with 4x109 CFU of Pseudomonas aeruginosa, and exposed to Laser radiation for 30 min /day along four successive days. The group F mice injected in the right thigh by both 0.2 ml from a suspension containing 106 cell/ ml of the Ehrlich tumor and 4x109 CFU of Pseudomonas aeruginosa. The group G injected in the right thigh by both 0.2 ml from a suspension containing 106 cell/ml of the Ehrlich tumor and 4x109 CFU of Pseudomonas aeruginosa and exposed to Laser radiation for 30 mins/day along four successive days. The tumor growth characteristics were followed for all animals. Cellular changes were evaluated using cells viability (ATP production) and cytokines expression (IFN- γ and IL-6) the treated and untreated tumors were studied and survival rate were demonstrated. The results showed that injection with the microorganism alone caused the death of all animals till fourth day. While, the mice with post tumor implantation (PI) which exposed to laser irradiation decreased the volume of the tumor. On the other hand, tumors infected with microorganisms then irradiated for 1 day post infection showed a sudden decrease in tumor volume during next three days of infection then the tumor began to grow again with higher rate. More than 70% of the animals survive till day 35 PI. The groups A, B, C and F in the 1st, 2nd, 3rd and 4th days produced a non significant increase in ATP luminescence. While, the groups D, E and G irradiated once at the 1st, 2nd, 3rd and 4th day produced a significant increase in ATP. In addition, the groups A, B, C and F cells showed a significant increase in the level production of IFN-γ and IL-6 in serum. Moreover, Irradiated groups D, E and G produced a significant change of both cytokines, but, the group G exhibited a highly significant increase in the production of IFN-γ and IL-6 in serum more than the groups D and E.